Recently there has been use of aluminum and/or aluminum alloys not only in the tins of heat exchangers, but also in the heat transfer tubes and/or the header pipes of heat exchangers, in order to reduce the weight of heat exchangers. Heat exchangers in which aluminum and/or an aluminum alloy are used for the fins, heat transfer tubes, and header pipes are referred to below as aluminum heat exchangers. Piping made from copper and/or a copper alloy (referred to below as copper piping) is used as piping for circulating refrigerant in aluminum heat exchangers.
In a heat exchanger for performing heat exchange between air and a refrigerant, the components of the heat exchanger have a lower temperature than the dew-point temperature of air, and dew condensation often occurs due to the moisture in the air. If dew condensation occurs in copper piping, there will be copper ions in the dew condensation water. When dew condensation water containing copper ions gets on an aluminum heat exchanger, it could lead to corrosion. Therefore, there are cases in which a falling water droplet preventative piping section inclined downward from the heat exchanger toward the refrigerant line is provided in order to prevent dew condensation water containing copper ions from dripping down onto the aluminum heat exchanger, as is indicated in Japanese Laid-open Patent Application No. 6-300303.